Oil-Rock Correlation And Hydrocarbon Generation From Middle-shallow Layer In South Songzhan

Since the commencement of exploration on the northern of Songliao Basin in 1955 to well Songji 3 in 1959 discovered with industrial oil flow, two sets of oil-bearing layers of Sanzhao Depression and the Fuyang Putaohua Layer Putaohua and Fuyang were confirmed. Since 1985, Shengping, Wangjiatun, Songzhan, Yushulin, Shangjia oil and gas field in Putaohua and Fuyang oil layers in the mid-shallow formation of Sanzhao have been found. In recent years, deep gas reservoir has been discovered. South Songzhan is located in the Central Depression of SongliaoBasin-Sanzhao Depression, however, at the present, the exploration in South Songzhan is still relatively low, geological understanding of a very shallow, the prospects for oil and gas resources not very clear.In this paper, applied organic geochemistry and petroleum geology theory, studied the characteristics of source rock in the South Songzhan, Sanzhao and Suihua depressions, evaluation of hydrocarbon source rocks was carried out. Research on the crude oil and source rock physical properties, ethnic composition n-alkane distribution and biomarkers in the Putaohua and Fuyang reservoir of Sanzhao Depression determined Putaohua, Fuyang oil sources. Combined with of geological conditions, Putaohua and Fuyang oil migration and accumulation models were set up.Studies also have shown that qn1 dark mudstone of the area is main hydrocarbon source rocks, then qn23 source rocks and the threshold of hydrocarbon generation is 1350m, hydrocarbon expulsion threshold is 1750m, so a part of Songzhan is located in source rocks region, the other part is outside the region. Through the hydrocarbon source rock evaluation and resources calculation, hydrocarbon generated in source rocks in intensity is up to 1100×104t/km2 from the mid-shallow formation of Sanzhao depression, hydrocarbon expulsion intensity is 160×104t/km2, source rocks contribute to the total volume of hydrocarbon generation is 1085.6×108t, the amount of hydrocarbon expulsion of 47.68×108t. In South Songzhan, hydrocarbon generated is up to 700×104t/km2, hydrocarbon expelled of 20×104t/km2, source rocks contribute to the total hydrocarbon generation volume of 23.31×108t, hydrocarbon expulsion of 0.12×108t. Meanwhile the timing of hydrocarbon generated and expelled from the Qingshankou source rock is determined as late Mingshui deposition to present. Oil-source correlation shows that Putaohua and Fuyang crude oil in south Songzhan is mature oil, they are all from the same oil source, mainly comes from the qn1 source rock in Sanzhao Depression, then qn23 source rocks. Combined with the research area surrounding geological conditions, Putaohua and Fuyang oil in South Songzhan exist two migration and accumulation models. The areas near T2 faults connecting source rock and reservoir in the region of source rock and the upper sides of faults near the path way of oil migration should be favorable for F,Y oil layers future exploration and the future exploration of Putaohua oil layer should be in the region of source rock.